Above: Three of the USGS scientists who participated in the Expand Your Horizons conference at the University of California, Santa Cruz. Pictured here is the "Echo to Image" team (left to right): Ginger Barth (team leader), Carol Reiss, and Nadine Golden; not pictured is Carissa Carter, who developed and led the "Sands, Storms, and Slope Failure" workshop.

On Saturday, March 4, 2006, U.S. Geological Survey (USGS) geoscientists Ginger Barth, Carissa Carter, Nadine Golden, and Carol Reiss presented two workshops representing careers in Coastal and Marine Geology and Geophysics at the 6th annual Expanding Your Horizons in Science, Mathematics and Engineering conference at the University of California, Santa Cruz (UCSC). The conference, open to girls in grades 8 through 12, included participation in the girls' choice of two hands-on workshops. A total of 15 workshops were offered, with topics as diverse as finding genes, mapping the ocean floor, neonatal nursing, satellite design, and organic farming. More than 200 girls attended the all-day event (for additional information, see Expanding Your Horizons).

The workshop developed by Barth, Reiss, and Golden, "Echo to Image: Revealing Hidden Landscapes Beneath the Sea," featured concepts in marine geology and geophysics. Girls looked at USGS bathymetric maps of the California margin, considered how looking down through layers of sediment is like looking backward in time, and used slinkies (coil-shaped toys) to create compressional waves like the sound waves used to map the sea floor. They also simulated seismic profiling by measuring depth to a volcano model buried in a pan of vermiculite, and they compared their results to a real seismic-reflection profile of a buried seamount in the Bering Sea. A final segment on drawing contour lines led the participants to create their own volcano maps. To wrap up, the vermiculite was removed, and the girls compared their profiles and contour maps with the real three-dimensional volcano model, with great satisfaction.

Girls who chose this workshop were predominantly 10th graders. They were polite, interested, and enthusiastic. All of the participantsincluding the university-student helpers and the conference organizerswere quite excited to see what beautiful landscapes lie beneath the sea, how physics and geology are intertwined in marine exploration, and how real people have a diversity of jobs exploring our Earth.

Above left: A pair of students use a wooden skewer to measure the distance from the "sea surface" (top of a pan of vermiculite) to the "sea floor" (a plastic model of a volcano hidden by the vermiculite). This exercise gave them a feel for how marine scientists map terrain that is hidden from view by seawater.

Above right: Girls enjoy using slinkies to create and visualize compressional waves, models for the sound waves used to measure and map undersea topography.

"Sand, Storms, and Slope Failure," the workshop developed by Carter along with UCSC graduate student Christie Rowe, was a hands-on lesson on landslides, one of the surficial processes particularly relevant to Santa Cruz County. Students experimented with various "slope" materials: sand, dirt, and gravel. First, they calculated the angle of repose for each material in dry and wet states. Using their results, they built upon the experiment and added "rain" to the top of each slope until failure occurred. This exercise inspired lively discussion about the amount and intensity of rain needed to cause slides in different materials, pore-space and pore-pressure considerations, and the varieties and styles of landslides.

Above left:
Students pleased with the results of their contouring, an exercise in which they transformed their plot of depth soundings into a contour map of the hidden volcano.

Above right:USGS scientist Carissa Carter (right) watches as students adjust their carefully engineered slope in preparation for adding "rainfall" (water) to see how much rain the slope can withstand before it fails (failure was defined as the first movement of one of the green houses or red hotels).

The workshop culminated in the girls working in groups to engineer slopes that would resist failure, and then measuring how much rain each slope could withstand. Using the knowledge from the earlier exercises, they mixed and layered substrates and engineered retaining walls and drainage networks. They positioned plastic models of houses and hotels on each slope. Failure was defined as the first movement of any house or hotel, and so building placement was also a factorsometimes only the toe of a slope will fail, damaging houses at or near the base of the slope, while houses nearer the top remain unscathed. Overall, the girls developed sophisticated solutions that engineers actually use to combat slope failure in Santa Cruz County.

Materials for the landslide experiment are easy to obtain, and the content can be modified for a variety of audiences to include more or less qualitative and quantitative content. In general, the 8th through 11th graders at this workshop were adept at the calculations. They were excited about the concept, and many asked questions about the types of classes to take in order to pursue careers in the geosciences.